1. Field of the Invention
The present invention relates to an apparatus and method for wrapping articles.
2. Description of the Related Art
Article wrapping devices are utilized for wrapping articles with a protective wrapper, such as paper, plastic foil or the like. Article wrapping devices are widely used in the publishing industry to wrap bundles of signatures, such as newspapers or magazines. Article wrapping devices have also been used to package consumer products.
A conventional wrapping device which is widely used in the publishing industry is a three-sided bottom wrapper. Bundles of signatures to be wrapped are conveyed on a series of generally horizontal successive conveyor belts. A roll of wrapping paper is positioned beneath the conveyor belts.
At a selected time, the roll feeds a leading edge of the wrapping paper upward through a feed slot between two of the successive conveyors. A mechanical gripping apparatus grips the leading edge of the wrapping paper with a clamp, and lifts it upwards with a hydraulic or pneumatic cylinder. The wrapping paper is thus lifted in an orientation which is generally perpendicular to the path of the oncoming bundle of signatures. When the bundle intersects the wrapping paper, the leading edge of the wrapping paper is released by the clamp, and drapes over a top side of the bundle. Simultaneously, a cutting device below the conveyors slices the dispensed wrapping paper from the roll. The trailing end of the dispensed wrapping paper is dragged beneath the bundle by its continued passage on the conveyor belts past the feed slot.
The mechanical gripping apparatus used to lift the sheet of wrapping material significantly increases the unit cost of the article wrapping device.
Maintaining and replacing such a mechanical gripping apparatus is costly and can result in unacceptable down time for the entire article wrapping device while the mechanical gripping device is maintained or overhauled.
The mechanical gripping apparatus also slows the throughput rate of the wrapping device. When a bundle has been wrapped and is exiting the device, the mechanical gripping apparatus must be lowered to grip the next sheet of wrapping paper to wrap the next bundle. This creates "dead time" in the cycle, because no follow-on bundle can be wrapped until the mechanical gripping apparatus is lowered and grips the next sheet of wrapping paper. Throughput of the wrapping device is thus inherently limited by the operation of the mechanical gripping apparatus.
It is an object of the present invention to provide a simple and reliable article wrapping device which does not require a mechanical gripping apparatus to grip the leading edge of the wrapping paper. Deletion of the mechanical gripping apparatus will minimize maintenance, eliminate a source of potential failure, and minimize the overall cost and down-time of the article wrapping device.
It is also an object to provide for increased throughput of the wrapping device, by eliminating the "dead time" associated with the operation of the mechanical gripping apparatus, and allowing a follow-on bundle to enter the device before the previous bundle has exited the device.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.